Due to the rise in the number of diabetic patients in recent years, it is recommended that diabetic patients perform self-monitoring of blood glucose by monitoring daily variations of blood glucose. For measuring blood glucose levels, a blood glucose measuring device for automatically measuring the amount of glucose in blood is used. Prior to measurement, it is necessary for the diabetic patient to sample his or her own blood.
Blood is sampled by puncturing the fingertip with a puncture needle, and thereafter pressing the region around the punctured spot with another finger or fingers to squeeze out the blood. The fingertip is punctured by a puncture set (see, for example, Patent Document 1) comprising a puncture needle unit having a puncture needle and a casing that houses the puncture needle therein, and a puncture device having a mount on which the puncture needle unit is detachably mounted and a plunger that is coupled to the puncture needle while the puncture needle unit is mounted on the mount. More specifically, the puncture needle unit is inserted into the puncture device and mounted in place, and then the puncture device with the puncture needle unit mounted therein is actuated to cause the puncture needle of the puncture needle unit to project and puncture the fingertip. After the puncture needle has punctured the fingertip, i.e., after the puncture needle has been used, the puncture needle unit is removed from the puncture device. The puncture set disclosed in Patent Document 1 is arranged to have a clearance (gap) between the casing of the puncture needle unit and the mount of the puncture device, for thereby allowing the puncture needle unit to be inserted easily into the puncture device upon insertion of the puncture needle unit into the puncture device.
However, when the puncture needle unit is inserted into the puncture device, due to the clearance, the puncture needle unit may be inserted obliquely into the puncture device. In such a case, the puncture needle unit does not become properly mounted in the puncture device, i.e., the puncture needle of the puncture needle unit and the plunger of the puncture device do not become coupled to each other, thus making it difficult to puncture the fingertip with the puncture set.
Patent Document 1: International Publication No. 2006/028096